Lect 5 - Mitochondrial genome and mutation

Question 1

define genome,

Answer 1

genome - entirety of an organisms hereditary information (23 pairs + 2 sex) but also mitochondrial DNA

Question 2

other than ATP production, what else is mitochondria involved in

Answer 2

signalling
differentiation
death
growth

Question 3

why is mitochondrial disorders only passed on by the mother

Answer 3

100 000 in egg

100 in sperm

Question 4

why are there mitochondrial mutations

Answer 4

no repair mechanism
increased free radical release

these lead to an accumulation of errors, on top of this, shorter mDNA replicate faster than normal DNA, causing mutations to progress at a faster rate

different cells will have different genetic sequence of mtDNA, leading to highly variable expression of mtDNA disease

mtDNA mutation most likely to affect CNS

Question 5

does mitochondrial disorders follow simple pedigree trees, why or why not

Answer 5

no these pedigree trees are much more complex and doesn’t follow the rules of normal inheritance. this is due to penetrance and expressivity

penetrance - does a disease or trait present? probability a given phenotype will present if phenotype related genotype is there.
expressivity - what is the severity of a disease or trait? or variation in phenotype among individuals carrying a particular genotype.

these are relevant because due to the nature of mtDNA replication, there are can be mutations differences between mtDNA in different cells, depending on how much mutation, and which ones are inherited, the penetrance and expressivity will be different.
other factors include gene-gene interactions, environmental factors, survivability